Metabolically stable vanillin derivatives for the treatment of hypoxia

ABSTRACT

Vanillin derivative compounds that bind covalently with hemoglobin are provided. Methods of treating sickle cell disease and other hypoxia-related disorders by administering such compounds are also provided.

This invention was made with government support under grant number R01 MD009124 awarded by the National Institutes of Health (NIH). The government has certain rights in the invention.

FIELD OF THE INVENTION

The invention is generally related to agents with hypoxic properties for treating disease. In particular, the invention provides hemoglobin-binding Michael Addition compounds with hypoxic properties that are suitable for treating sickle cell disease (SCD), as well as several hypoxia-underlying diseases including, but not limited to, acute respiratory distress syndrome (ARDS), hemorrhagic and traumatic shock, cardiac arrest and cardiogenic shock, traumatic brain injury, stroke, cancer, myocardial infarction, myocardial ischemia, and vaso-occlusive crisis (VOC).

BACKGROUND OF THE INVENTION

Sickle cell disease (SCD) is the most common inherited hematologic disorder affecting over 100,000 people in the U.S. and over 15 million worldwide.^(1,2) The number of affected persons is projected to increase by 30% by 2050.² SCD results from a single-point hemoglobin (Hb) mutation: βGlu6→βVa16 that changes normal Hb (HbA) into sickle Hb (HbS). Under hypoxic conditions, deoxygenated HbS (Deoxy-HbS) polymerizes into long, rigid fibers, causing sickling of red blood cells (RBCs). The low oxygen affinity (low O₂-affinity) of HbS, presumably due to elevation of the natural Hb allosteric effector, 2,3-diphosphoglycerate (2,3-DPG) and/or SIP exacerbates the hypoxia-induced polymerization exacerbates the hypoxia-induced polymerization.³⁻⁹ While the primary interaction in HbS fiber formation occurs between the βVa16 residue and a hydrophobic pocket on an adjacent HbS tetramer, stability of the fiber requires additional intermolecular interactions between the HbS tetramers.¹⁰⁻¹⁵ The rigid RBCs impair blood flow, causing hemolysis and vaso-occlusion, which leads to a cascade of secondary adverse effects, e.g., adhesion of RBCs to tissue endothelium, hemolysis, oxidative stress, decreased vascular nitric oxide (NO) bioavailability, inflammation, painful VOC crisis, and eventually chronic endothelial and organ damage that ultimately leads to poor quality of life and decreased life expectancy.^(1,2,16-18)

Until recently, Hydroxyurea (HU), which induces fetal Hb (HbF) production was the only approved drug for treating SCD¹⁹. HbF modulates clinical severity of SCD by directly inhibiting HbS polymerization. However, a reported lack of response to HU in up to 30% of patients and perhaps, poor compliance, tend to limit its use.^(20,21) The past few years have seen three new drugs approved by the FDA for the treatment of SCD. These include L-glutamine (Endari) in 2017 to treat SCD in the US, however, the European regulatory body recommended against approval of the medication due to limited evidence of efficacy in Phase III trials.^(22,23) L-glutamine increases the amount of reduced form nicotinamide adenine dinucleotide (NADH) in erythrocytes, which may allow sickle RBCs to more appropriately maintain homeostasis in the face of abundant oxidative stress, and could result in fewer painful crises and adverse events.²⁴ In 2019, Crizanlizumab (Adakveo)²⁵ and Voxelotor²⁶ (Oxbryta, aka GBT440) were approved. Crizanlizumab is a first-in-class monoclonal antibody targeting P-selectin, which is implicated in the pathologic endothelial adhesion of sickle erythrocytes and leukocytes, and has been shown in clinical trials to reduce the frequency of painful vaso-occlusive crises.²⁵ The anti-sickling agent, Voxelotor was first of a new class of aromatic aldehyde-containing compounds (AEHs) that binds to Hb to prevent HbS polymerization by increasing Hb oxygen (O₂) affinity with concomitant antisickling effect.²⁷⁻³⁰.

Hemoglobin (Hb) functions in equilibrium between the unliganded or deoxygenated (Deoxy) tense (T) state, which exhibits low affinity for ligand, and the liganded or oxygenated relaxed (R) state, which exhibits high affinity for ligand. The degree of shift in the oxygen equilibrium curve (OEC) is reported as a decrease (left-shift) or increase (right-shift) in P₅₀ (oxygen tension at 50% Hb O₂ saturation). Only T-state Deoxy HbS can be incorporated into insoluble fibers, and thus, the kinetics of HbS polymerization and RBC sickling are favored primarily in hypoxic conditions. Hence, allosteric modulation compounds that not only destabilizes the T-state, but also stabilizes the O₂-liganded quaternary R-state promotes increased O₂ affinity, preventing HbS from forming insoluble fibers.^(27-29,31-33)

Several aromatic aldehydes, e.g. Voxelotor,²⁶ 5-HMF, vanillin and its derivatives (e.g. INN-312, SAJ-310, and TD-7)^(27-32,34-37) are known to have this allosteric and/or pharmacologic property by forming a Schiff-base covalent interaction with the N-terminal αVa11 nitrogens at the α-cleft of Hb that stabilize the R-state Hb and/or destabilize the T-state Hb, making them potential antisickling agents for the treatment of SCD. As noted above, Voxelotor is approved for the treatment of SCD, and although showed increased Hb levels and reduced hemolysis in SCD patients,²⁶ these surrogate end-points are not long-term clinical outcomes. However, the study provided encouraging evidence that Hb-binding agents may have disease-modifying potential. Vanillin, and several of its derivatives, e.g. INN-312, TD-7, and SAJ-310 have been studied in the preclinic, and found to prevent hypoxia-induced RBC sickling.³⁴⁻³⁷ Unfortunately, these compounds undergo significant and rapid metabolic oxidation of the aldehyde moiety,³⁴⁻³⁷ resulting in poor pharmacokinetic (PK) properties, precluding their development into viable therapeutic agents. The thiazolidine complex of Vanillin where the aldehyde is protected by L-cysteine extended Vanillin half-life 2-fold in-vivo.³⁸ Unlike Vanillin and Voxelotor that act exclusively via O₂-dependent mechanism to prevent hypoxia-induced RBC sickling, INN-312 exhibits both O₂-dependent and O₂-independent antisickling activities, the latter mechanism of action due to disruption of key intermolecular contacts necessary for stable polymer formation.^(34,36) This novel dual mechanism of action has the potential to provide for even more potent anti-sickling effects with better clinical outcomes.

Several non-aromatic aldehyde compounds have also been studied for their antisickling potentials. These compounds, unlike aromatic aldehydes effect their antisickling activities by covalently binding to the surface-located βCys93 of Hb to destabilize the T-state Hb, resulting in increased Hb oxygen affinity.³⁹ These compounds are also expected to directly destabilize the polymer by virtue of binding to the surface of the Hb. An example of βCys93 binder is Ethacrynic acid (ECA).³⁹ However, the diuretic activity of ECA precludes its use as an oral therapeutic agent for the treatment of SCD.³⁹ Thiol derivatives that also bind to βCys93 are currently being studied to treat SCD.^(40,41)

Although, significant progress has been made in developing compounds to treat SCD, there is still a pressing need to provide safer, less expensive, easily administered and more effective therapeutic agents to treat SCD patients, particularly agents that could mitigate vaso-occlusion, pain, and ameliorate organ damage. These agents, unlike aromatic aldehydes, must be resistant to oxidative metabolism, form more stable covalent adduct, and importantly prevent RBC sickling via both O₂-dependent and O₂-independent mechanisms of action.

SUMMARY

An aspect of the disclosure provides vanillin derivatives containing reactive centers that are metabolically stable and capable of forming stable covalent interactions with Hb. In some embodiments, the compounds possess enhanced pharmacokinetic (PK) properties and exhibit both O₂-dependent and O₂-independent antisickling mechanisms of action.

Another aspect of the disclosure provides a pharmaceutical composition comprising a compound as described herein and a pharmaceutically acceptable carrier.

Another aspect of the disclosure provides a method of treating a hypoxia-associated disease or condition in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a compound as described herein. In some embodiments, the hypoxia-associated disease or condition is selected from the group consisting of acute respiratory distress syndrome (ARDS), hemorrhagic shock, traumatic shock, cardiac arrest, cardiogenic shock, traumatic brain injury, stroke, cancer, myocardial infarction, myocardial ischemia, and vaso-occlusive crisis.

Another aspect of the disclosure provides a method of treating sickle cell disease in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a compound as described herein. In some embodiments, the therapeutically effective amount of said compound is sufficient to inhibit red blood cell (RBC) sickling. In some embodiments, the compound is resistant to oxidative metabolism. In some embodiments, the inhibiting of said RBC sickling occurs via both O₂-dependent and O₂-independent mechanisms of actions.

The vanillin-like covalent modifiers of this invention, unlike vanillin, are non-aldehydes. However, they contain reactive centers that are metabolically stable and capable of forming stable covalent interactions with Hb. These compounds would also possess enhanced pharmacokinetic (PK) properties, and may exhibit both O₂-dependent and O₂-independent antisickling mechanism of action. Unlike Vanillin that forms Schiff-base interaction with the N-terminal αVa11 amine at the α-cleft of the protein, these novel compounds may bind covalently with Hb through a Michael addition reaction with βCys93 to stabilize the R-state and/or destabilize the T-state Hb. In some instances, the compounds may also bind with the free N-terminal αVa11 amine at the α-cleft of the protein to stabilize the R-state Hb. Covalent binding to Hb that stabilize the R-state Hb and/or destabilize the T-state Hb should lead to increase in the protein's affinity for oxygen and concomittantly prevent hypoxia-related HbS polymerization and RBC sickling. These compounds, also by virtue of binding to βCys93, which is located on the surface of the molecule, should exhibit an O₂-independent antisickling effect by directly destabilizing the polymer. Additionally, these compounds should exhibit several secondary pharmacologic effects, including prevention of oxidative stress, hemolysis, inflammation, vaso-occlusion, and increasing oxygenation of hypoxic tissues. The covalent binding nature, extended therapeutic duration of action because of resistance to metabolism, and the multiple therapeutic effects of these compounds also advantageously decrease the therapeutic dose required for efficacy, compared to Vanillin

Other features and advantages of the present invention will be set forth in the description of invention that follows, and in part will be apparent from the description or may be learned by practice of the invention. The invention will be realized and attained by the compositions and methods particularly pointed out in the written description and claims hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Structures of example metabolically stable vanillin derivatives according to some embodiments of the disclosure.

FIG. 2. Antisickling effect of MMA-200 series of compounds on intact SS cells. Dotted bar, diagonal line bar and solid bar denote compound concentrations of 1 mM, 2 mM and 5 mM, respectively. Only MMA-202 was tested at 1 mM. Weave bar denotes control (no compound). n=2 to 8.

FIGS. 3A-C. Images of Sickled Cells in the (A) absence or presence of (B) MMA-202 or (B) MMA-205 under 2.5% O₂ Gas.

FIG. 4. Degree of shift in Hb oxygen affinity (ΔP₅₀ ) by MMA-200 series of compounds on intact SS cells. Diagonal line bar, and solid bar denote compound concentrations of 2 mM and 5 mM, respectively. n=2.

FIG. 5. Oxygen equilibrium curve of 0 mM (control), 2 mM, and 5 mM MMA-202 of intact SS cells.

FIG. 6. Oxygen equilibrium curve of 0 mM (control), 2 mM, and 5 mM MMA-204 of intact SS cells.

FIG. 7. Oxygen equilibrium curve of 0 mM (control), 2 mM, and 5 mM MMA-205 of intact SS cells.

FIGS. 8A-C. Cation exchange HPLC of 0 mM (control), 2 mM and/or 5 mM of (A) MMA-202, (B) MMA-204, (C) MMA-205 after incubation with intact SS Cells.

FIGS. 9A-C. Reverse-phase HPLC of 0 mM (control), 2 mM and/or 5 mM of (A) MMA-202, (B) MMA-204, (C) MMA-205 after incubation with intact SS Cells.

FIG. 10. Time-dependent modification of Hb in normal whole blood incubated with test compounds (n=2). Solid line is Vanillin, dotted line is MMA-202, and long dash line is DMSO (1%). N=1 or 2.

DETAILED DESCRIPTION

The compounds disclosed herein comprise a metabolically stable reactive center which makes the compounds resistant to oxidative metabolism and allows formation of a covalent adduct interaction with a Hb protein, including HbS, with greater stability. In addition, the compounds may inhibit RBC sickling via both O₂-dependent and O₂-independent mechanisms.

In some embodiments, the compounds disclosed herein have the generic formula of Formula I:

wherein R₆ is a substituted or unsubstituted amide, substituted or unsubstituted ester, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted alkyl halide, carboxyl or substituted or unsubstituted carbonyl;

wherein A, B, D and E are the same or different and are independently C, O, S, or N;

wherein R₁, R₂, R₃, R₄ and R₅ are the same or different and are independently any of

-   -   i) H, OH, or halogen,     -   ii) substituted or unsubstituted amine, substituted or         unsubstituted ester, substituted or unsubstituted ether,         substituted or unsubstituted alkyl, substituted or unsubstituted         aryl, substituted or unsubstituted alkoxy, substituted or         unsubstituted O-aryl, or cyano, and     -   iii) a moiety of the general formula:

-   -   wherein R₇ and R₈ are the same or different and are         independently H, OH, a halogen, a substituted or unsubstituted         alkyl, a substituted or unsubstituted alkoxy, a substituted or         unsubstituted hydroxyl-alkyl, a substituted or unsubstituted         aryl, or a substituted or unsubstituted O-aryl;     -   wherein X, Y and Z are independently a substituted or         unsubstituted C or N (e.g., phenyls, pyridyls or other         heterocyclics);     -   wherein G is a saturated or unsaturated bridging or linking         chain of 1 to 10 atoms in length wherein at least some atoms or         atomic groups in G are selected from the group consisting of C,         CH₂, CO, O, S, NH, NHCO, NHCONH, and OCO, wherein the asterisk         marks the point of attachment to the six membered ring of         Formula 1, and wherein M is substituted or unsubstituted.

Exemplary substitutions of G include but are not limited to halogens, halogenated alkyls, amines, sulfyls, alkyls, esters, and ethers. G may be 2 to 8 atoms in length. An exemplary substituted carbonyl would include but not be limited to a carboxylic acid moiety. Exemplary compounds within the practice of this invention are depicted in FIG. 1.

As used herein, any “R” group(s) such as, without limitation, R, R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, and so on represent substituents that can be attached to the indicated atom. An R group may be substituted or unsubstituted.

The term “alkyl” refers to a straight or branched hydrocarbon chain that includes a fully saturated (no double or triple bonds) hydrocarbon group. The alkyl group may have 1 to 20 carbon atoms (whenever it appears herein, a numerical range such as “1 to 20” refers to each integer in the given range; e.g., “1 to 20 carbon atoms” means that the alkyl group may consist of 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to and including 20 carbon atoms, although the present definition also covers the occurrence of the term “alkyl” where no numerical range is designated). The alkyl group may also be a medium size alkyl having 1 to 10 carbon atoms. The alkyl group could also be a lower alkyl having 1 to 6 carbon atoms. The alkyl group of the compounds may be designated as “C₁-C₄ alkyl” or similar designations. By way of example only, “C₁-C₄ alkyl” indicates that there are one to four carbon atoms in the alkyl chain, i.e., the alkyl chain is selected from methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, and t-butyl. Typical alkyl groups include, but are in no way limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl and hexyl. The alkyl group may be substituted or unsubstituted.

The term “alkenyl” refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more double bonds. An alkenyl group may be unsubstituted or substituted.

The term “alkynyl” refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more triple bonds. An alkynyl group may be unsubstituted or substituted.

The term “substituted” refers to, for example, an alkyl group substituted by, for example, about one, two three or four substituents, examples of which include but are not limited to: halo, hydroxy, alkoxy, oxo, alkanoyl, aryloxy, alkanoyloxy, amino, alkylamino, substituted alkylamino, cycloalkylamino, substituted cycloalkylamino, arylamino, substituted arylamino, aralkylamino, substituted aralkyamino, disubstituted amines in which the 2 amino substituents are selected from alkyl, aryl or aralkyl; alkanoylamino, aroylamino, aralkanoylamino, substituted alkanoylamino, substituted arylamino, substituted aralkanoylamino, thiol, alkylthio, arylthio, aralkylthio, alkylthiono, arylthiono, aralkylthiono, alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, sulfonamido, e.g. SO₂NH₂, substituted sulfonamido, nitro, cyano, carboxy, carbamyl, e.g. CONH₂, substituted carbamyl e.g. CONHalkyl, CONHaryl, CONHaralkyl or cases where there are two substituents on the nitrogen selected from alkyl, aryl or aralkyl; alkoxycarbonyl, aryl, substituted aryl, guanidino, heterocyclyl, e.g., indolyl, imidazolyl, furyl, thienyl, thiazolyl, pyrrolidyl, pyridyl, pyrimidyl, pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl, homopiperazinyl and the like, and substituted heterocyclyl. These substituents may be further substituted, e.g. with alkyl, alkoxy, aryl, aralkyl, etc.

The term “alkoxyl” refers to a radical of —O-alkyl.

The term “alkyl halide” refers to an alkyl group in which one or more of the hydrogen atoms are replaced by a halogen (e.g., mono-haloalkyl, di-haloalkyl and tri-haloalkyl). Such groups include but are not limited to, chloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl and 1-chloro-2-fluoromethyl, 2-fluoroisobutyl. A haloalkyl may be substituted or unsubstituted.

The term “amine” refers to nitrogen-containing groups, such as NH₃, NH₂, and NR¹R², wherein R¹ and R² can each be independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, and aralkyl, alkylene, arylene, aralkylene. Thus, “amine” as used herein can refer to a primary amine, a secondary amine, or a tertiary amine.

The term “halogen” or “halo” refers to, e.g. fluorine, chlorine, bromine and iodine.

The term “aryl” refers to compounds which contain an aromatic group, e.g. a monocyclic or polycyclic aromatic compound. Monocyclic aryls generally have about 4 to about 7 carbon atoms, bicyclic aryls may have e.g. from about 7 to about 11 carbon atoms, and tricyclic aryls may contain from about 10 to about 15 or more carbon atoms. Exemplary aryls are or comprise groups that include but are not limited to: phenyl, naphthyl, biphenyl (diphenyl), thienyl, indolyl, etc. Aryls may be substituted or unsubstituted, and may or may not include one or more heteroatoms (e.g. S, N, etc.) in one or more ring structures (heteroaryls).

The term “arylalkyl” refers to an aryl or a substituted aryl group bonded directly to an alkyl group, such as benzyl.

The term “substituted aryl” refers to an aryl group substituted by, for example, about one to about four (e.g. 1, 2, 3, or 4) substituents such as alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, aralkyl, halo, trifluoromethoxy, trifluoromethyl, hydroxy, alkoxy, alkanoyl, alkanoyloxy, aryloxy, aralkyloxy, amino, alkylamino, arylamino, aralkylamino, dialkylamino, alkanoylamino, thiol, alkylthio, ureido, nitro, cyano, carboxy, carboxyalkyl, carbamyl, alkoxycarbonyl, alkylthiono, arylthiono, arylsulfonylamine, sulfonic acid, alkysulfonyl, sulfonamido, aryloxy and the like. The substituent may be further substituted by hydroxy, halo, alkyl, alkoxy, alkenyl, alkynyl, aryl or aralkyl.

The term “carbonyl group” refers to a C=0 group.

The term “carboxyl group” refers to a COOH group.

The term “cyano” group refers to a “—CN” group.

The terms “heterocycle” and “heterocyclic” refer to an optionally substituted, fully saturated or unsaturated, aromatic or nonaromatic cyclic group which, for example, is a 4 to 7 membered monocyclic, 7 to 11 membered bicyclic, or 10 to 15 membered tricyclic ring system, which has at least one heteroatom in at least one carbon atom-containing ring. Each ring of the heterocyclic group containing a heteroatom may have 1, 2 or 3 heteroatoms selected from nitrogen atoms, oxygen atoms and sulfur atoms, where the nitrogen and sulfur heteroatoms may also optionally be oxidized and the nitrogen heteroatoms may also optionally be quaternized. The heterocyclic group may be attached at any heteroatom or carbon atom.

The term “heteroatoms” shall include at least oxygen, sulfur and nitrogen.

Exemplary compounds of this invention may form salts which are also within the scope of this disclosure. Pharmaceutically acceptable (i.e. non-toxic, physiologically acceptable) salts are preferred, although other salts are also useful, e.g., in isolating or purifying the compounds of this disclosure.

“Salts” or “pharmaceutically acceptable salts” refers to the relatively non-toxic, inorganic and organic acid addition salts, and base addition salts, of compounds of the present disclosure. These salts can be prepared in situ during the final isolation and purification of the compounds. In particular, acid addition salts can be prepared by separately reacting the purified compound in its free base form with a suitable organic or inorganic acid and isolating the salt thus formed. Exemplary acid addition salts include the hydrobromide, hydrochloride, sulfate, bisulfate, phosphate, nitrate, acetate, oxalate, valerate, oleate, palmitate, stearate, laurate, borate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylate, mesylate, glucoheptonate, lactiobionate, sulfamates, malonates, salicylates, propionates, methylene-bis-.beta.-hydroxynaphthoates, gentisates, isethionates, di-p-toluoyltartrates, methanesulfonates, ethanesulfonates, benzenesulfonates, p-toluenesulfonates, cyclohexylsulfamates and laurylsulfonate salts, and the like. See, for example S. M. Berge, et al., “Pharmaceutical Salts,” J. Pharm. Sci., 66, 1-19 (1977) which is incorporated herein by reference. Base addition salts can also be prepared by separately reacting the purified compound in its acid form with a suitable organic or inorganic base and isolating the salt thus formed. Base addition salts include pharmaceutically acceptable metal and amine salts. Suitable metal salts include the sodium, potassium, calcium, barium, zinc, magnesium, and aluminum salts. The sodium and potassium salts are preferred. Suitable inorganic base addition salts are prepared from metal bases which include sodium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, aluminum hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide and the like. Suitable amine base addition salts are prepared from amines which have sufficient basicity to form a stable salt, and preferably include those amines which are frequently used in medicinal chemistry because of their low toxicity and acceptability for medical use such as ammonia, ethylenediamine, N-methyl-glucamine, lysine, arginine, ornithine, choline, N,N′-dibenzylethylenediamine, chloroprocaine, diethanolamine, procaine, N-benzylphenethylamine, diethylamine, piperazine, tris(hydroxymethyl)-aminomethane, tetramethylammonium hydroxide, triethylamine, dibenzylamine, ephenamine, dehydroabietylamine, N-ethylpiperidine, benzylamine, tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, ethylamine, basic amino acids, e.g., lysine and arginine, and dicyclohexylamine, and the like

A solvate is the result of solvation which is an interaction of a solute (i.e. compound of the disclosure) with a solvent. Solvation leads to stabilization of the solute species in the solution. A solvate refers to the solvated state, whereby an ion in a solution is surrounded or complexed by solvent molecules. Exemplary solvents include, but are not limited to, propylene glycol; polypropylene glycol; polyethylene glycol (for example, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 900, polyethylene glycol 540 (all available from Union Carbide) and the like); pharmaceutically acceptable alcohols (for example, ethanol or 2-(2-ethoxyethoxy)ethanol (Transcutol®, Gattefosse, Westwood, N.J. 07675) and the like); polyoxyethylene castor oil derivatives (for example, polyoxyethyleneglycerol triricinoleate or polyoxyl 35 castor oil (Cremophor®EL, BASF Corp.), polyoxyethyleneglycerol oxystearate (Cremophor®RH 40 (polyethyleneglycol 40 hydrogenated castor oil) or Cremophor®RH 60 (polyethyleneglycol 60 hydrogenated castor oil), BASF Corp.) and the like); fractionated coconut oil (for example, mixed triglycerides with caprylic acid and capric acid (Miglyol®812, available from Huls AG, Witten, Germany) and the like); Tween®80; isopropyl palmitate; isopropyl myristate; pharmaceutically acceptable silicon fluids; and the like.

The compounds may be combined with pharmaceutically acceptable excipients. “Pharmaceutically” or “pharmaceutically acceptable” refer to molecular entities and compositions that do not produce an adverse, allergic or other untoward reaction when administered to a mammal, especially a human, as appropriate. A pharmaceutically acceptable carrier or excipient refers to a non-toxic solid, semi-solid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type.

In some embodiments, the compound of formula I has the formula:

The compounds described herein are useful for the treatment of diseases that can be ameliorated by increasing Hb oxygen affinity, for example, SCD (which may also be referred to as “sickle cell anemia”), and hypoxia-underlying or associated diseases, e.g. hemorrhagic and traumatic shock, cardiac arrest and cardiogenic shock, traumatic brain injury, cancer, stroke, myocardial infarction, myocardial ischemia, vaso-occlusive crisis, etc. The treatment methods disclosed herein may include a step of diagnosing a subject with SCD or hypoxia-underlying diseases, e.g. hemorrhagic and traumatic shock, cardiac arrest and cardiogenic shock, traumatic brain injury, cancer, stroke, myocardial infarction, myocardial ischemia, vaso-occlusive crisis, etc. The compounds described herein can also be used to increase tissue oxygenation or as a means to hyperoxygenate tumors making them more susceptible to radiation therapy.

The methods of the disclosure can be used to treat any patient or subject suffering from or likely to suffer from a disease or condition which can be prevented, treated, cured, or ameliorated (i.e. disease symptoms are abated) by increasing oxygenation to hypoxic tissues. Various embodiments or scenarios of use of the methods of the invention include but are not limited to patients who have incurred an acute or chronic illness or injury in which the body has become hypoxic. The agents act to enhance oxygen delivery from hemoglobin to the hypoxic tissue.

The methods of the disclosure involve administering compositions comprising at least one (i.e. one or more) of the compounds disclosed herein to a patient in need thereof. The present disclosure thus also provides compositions which comprise the compounds as described herein, usually together with a pharmacologically suitable carrier or diluent. In some embodiments, one substantially purified compound is present in a composition; in other embodiments more than one compound is present, each compound being substantially purified prior to being mixed in the composition. The preparation of pharmacologically suitable compositions for use as medicaments is well known to those of skill in the art. Typically, such compositions are prepared either as liquid solutions or suspensions, however solid dry forms such as tablets, pills, powders and the like are also contemplated. The liquid may be an aqueous liquid. Solid forms suitable for solution in, or suspension in, liquids prior to administration may also be prepared. The preparation may also be emulsified. The active ingredients may be mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredients. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol and the like, or combinations thereof. In addition, the composition may contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents, and the like. If it is desired to administer an oral form of the composition, various thickeners, flavorings, diluents, emulsifiers, dispersing aids or binders and the like may be added. The composition of the present disclosure may contain any such additional ingredients so as to provide the composition in a form suitable for administration. The final amount of compound in the formulations may vary. However, in general, the amount in the formulations will be from about 1% to about 99%.

The compound compositions (preparations) of the present disclosure may be administered by any of the many suitable means which are well known to those of skill in the art, including but not limited to: by injection, inhalation, orally, intravaginally, intranasally, by ingestion of a food or product containing the compound, topically, as eye drops, via sprays, etc. In exemplary embodiments, the mode of administration is orally or by injection. In addition, the compositions may be administered in conjunction with other treatment modalities which are used to treat SCD or other conditions associated with hypoxia, examples of which include but are not limited to the administration of hydroxyurea, L-glutamine (Endari), Crizanlizumab (Adakveo), Voxelotor (Oxbryta, aka GBT440), vanillin, supplemental oxygen, allosteric effectors of Hb, including those that increase the oxygen affinity of hemoglobin, e.g. 5-HMF, agents that decrease Hb affinity for oxygen, e.g. RSR13, etc.

The compositions of the present disclosure may also contain other components such as, but not limited to, additives, adjuvants, buffers, tonicity agents, and preservatives. In any of the compositions of this disclosure, the mixtures are preferably formulated at about pH 5 to about pH 8. This pH range may be achieved by the addition of buffers to the composition. It should be appreciated that the compositions of the present disclosure may be buffered by any common buffer system such as phosphate, borate, acetate, citrate, carbonate and borate-polyol complexes, with the pH and osmolality adjusted in accordance with well-known techniques to proper physiological values.

Embodiments of the disclosure also include methods of preparing the compounds and compositions disclosed herein. Various suitable methods are known in the art.

A patient or subject to be treated by any of the compositions or methods of the present disclosure can mean either a human or a non-human animal including, but not limited to dogs, horses, cats, rabbits, gerbils, hamsters, rodents, birds, aquatic mammals, cattle, pigs, camelids, and other zoological animals.

In some embodiments, the compound is administered to the subject in a therapeutically effective amount. By a “therapeutically effective amount” is meant a sufficient amount of active agent to treat the disease or disorder at a reasonable benefit/risk ratio applicable to any medical treatment. It will be understood that the total daily usage of the compositions of the present invention will be decided by the attending physician within the scope of sound medical judgment. The specific therapeutically effective dose level for any particular subject will depend upon a variety of factors including the disorder being treated and the severity of the disorder; activity of the specific compound employed; the specific composition employed, the age, body weight, general health, sex and diet of the subject; the time of administration, route of administration, and rate of excretion of the specific compound employed; the duration of the treatment; drugs used in combination or coincidental with the specific active agent employed; and like factors well known in the medical arts. For example, it is well within the skill of the art to start doses of the compound at levels or frequencies lower than those required to achieve the desired therapeutic effect and to gradually increase the dosage or frequency until the desired effect is achieved. However, the daily dosage of the active agent may be varied over a wide range from 0.01 to 1,000 mg per adult per day. In particular, the compositions contain 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 mg of the compound, including all multiples of 5 and 10 between 0.01 and 1000 (e.g. 100, 105, 110, 115, etc.). An effective amount of the drug is ordinarily supplied at a dosage level from 0.0002 mg/kg to about 20 mg/kg of body weight per day, especially from about 0.001 mg/kg to 7 mg/kg of body weight per day.

Before exemplary embodiments of the present invention are described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.

The invention is further described by the following non-limiting examples which further illustrate the invention, and are not intended, nor should they be interpreted to, limit the scope of the invention.

Example 1. Synthesis of Compounds

Melting point was performed using OptiMelt Automated Melting Point System Digital Image; Processing Technology SRS, Stanford Research Systems (Sunnyvale, Calif., USA); NMR spectroscopy was recorded on Bruker AVANCE III 400 (Bruker, Fällanden, Switzerland); LCMS spectroscopy was performed on Agilent Technologies 1260 Infinity LC/MSD system with DAD¥ELSD Alltech 3300 and Agilent; LC¥MSD G6120B mass-spectrometer (Santa Clara, Calif., USA); High-resolution mass spectroscopy (HRMS) was performed by separation and mass spectrometric detection techniques and were performed with an Infinity 1260 UHPLC system (Agilent Technologies, Waldbronn, Germany) coupled to an 6224 Accurate Mass TOF LC/MS system (Agilent Technologies, Singapore). Chromatographic separation was achieved using Agilent Zorbax C18 column (100 mm× 2.1 mm, 1.9 μm particle size). Mobile phase A consisted of 0.1% formic acid in water and mobile phase B consisted of 0.1% formic in acetonitrile. Injection volume of the samples solutions was 1 μL. Separation was performed at a constant flow rate of 0.4 ml/min at 40° C. A linear gradient started at 5% mobile phase B and ramped to 95% in 6.5 min, flushed 1.5 minute at 95% B. The column was re-equilibrated for 2 min with 5% mobile phase A. Positive ion mass spectra of the column eluate were recorded in the range of m/z 100-1500 at a measuring frequency of 9500 transients/s and a detection frequency of 4 GHz. The Agilent ion source was operated using the following conditions: pressure of nebulizing gas (N2) was 40 psi; temperature and flow rate of drying gas (N2) was 320° C. and 61/min, respectively; The capillary voltage was set to 4 kV, the fragmentor potential to 120V and the skimmer potential to 75 V. Solvents and chemicals were HPLC grade. Water was purified by Millipore Water Purification System. All the chemicals, reagents and solvents had been purified and/or dried in according to well-known literature methods; vendors' names: UORSY and Enamine (Kiev, Ukraine).

Synthesis of the MMA-200 Series of Compounds—

Preparation of methyl 2-(4-methoxyphenyl)-2-oxoacetate (MMA-201):

To a solution of 2-(4-methoxyphenyl)-2-oxoacetic acid (224 mg, 1.2 mmol) and K₂CO₃ (500 mg, 3.6 mmol) in DMF (20 mL) was added dropwise MeI (511 mg, 3.6 mmol) at 0° C. and the mixture was stirred at room temperature for 2 h. After quenching with 1 N HCl aq. (to pH˜7), the resulting mixture was extracted with MTBE (3×20 mL). The organic layers were combined, washed with sat.solution of NaHCO₃ (2×20 mL) and brine (15 mL), dried over Na₂SO₄, and concentration in vacuo. The resulting residue was purified by silica gel chromatography (EtOAc/hexane) to give methyl 2-(4-methoxyphenyl)-2-oxoacetate (MMA-201) (158 mg, 0.79 mmol, yield 62%). Melting point 49° C.; ¹H NMR (400 MHz, Chloroform-d) δ 7.99 (d, J=9.0 Hz, 2H), 6.95 (dd, J=9.4, 2.7, 2.3 Hz, 1H), 3.88 (s, 3H). ¹³C NMR (126 MHz, Chloroform-d) δ 184.43, 165.08, 164.35, 132.64, 125.47, 114.25, 55.65, 52.66. LC-MS (ESI), RT=1.283 min, m/z 135.00 [M-C₂ H₃O₂]⁺; HRMS (ESI), RT=5.586 min, m/z 195.0654 [M+H]⁺, formula C₁₀H₁₀O₄.

Preparation of 1-(4-methoxyphenyl)prop-2-en-1-one (MMA-202)

To a suspension of powdered aluminum chloride (0.723 g, 5.42 mmol) in dry DCE (40 mL) was added slowly 3-chloropropionyl chloride 2(0.455 mL, 4.74 mmol) at 0° C. and anisole 1 (0.491 mL, 4.52 mmol) under cooling with water. The orange solution was stirred at room temp. for 3 h and left standing for about 12 h. The dark orange solution was poured onto ice (20 g), the organic layer separated and the aqueous layer extracted two times with CH₂Cl₂. The collected organic phases were washed with water (2×20 mL), several times with aqueous NaOH (2%, 50 mL) until the organic phase did not turn back to yellow, and then twice with water (10-15 mL). The organic phase was dried over MgSO4 and the solvent removed under reduced pressure. Purification by gradient column chromatography [SiO₂, CH₂Cl₂/petroleum ether (40/60), 20:1 to CH₂Cl₂] gave 0.923 g (97% yield) of 3-chloro-1-(4-methoxyphenyl)propan-1-one as a colourless solid.

0.83 mL TEA was added to solution of compound 3-chloro-1-(4-methoxyphenyl)propan-1-one in 20 mL CH₃CN, stirred and refluxed for 1 h. Then the reaction mixture was cooled, concentrated in vacuo, added 50 mL H₂O and extracted with DCM (3×10 mL). The organic layers was combined, washed with water (2×5 mL), dried over Na₂SO₄, filtrated and the solvent removed under reduced pressure at rt. Purification by gradient column chromatography [SiO₂, CH₂Cl₂/petroleum ether (40/60), 20:1 to CH₂Cl₂] gave 0.562 g from MMA-202 (78% yield). Melting point 20° C.; ¹H NMR (400 MHz, Chloroform-d) δ 7.93 (d, J=8.8 Hz, 2H), 7.14 (dd, J=17.0, 10.5 Hz, 1H), 6.93 (d, J=8.8 Hz, 2H), 6.39 (dt, J=17.1, 1.5 Hz, 1H), 5.84 (dt, J=10.5, 1.5 Hz, 1H), 3.84 (s, 3H); ¹³C NMR (126 MHz, Chloroform-d) δ 189.21, 163.55, 132.14, 131.02, 130.21, 129.22, 113.85, 55.48; LC-MS (ESI), RT=1.162 min, m/z 163.00+[M+H]⁺; HRMS (ESI), RT=5.487 min, m/z 163.0752[M+H]⁺, formula C₁₀H₁₀O₂.

Preparation of 2-(4-methoxyphenyl)-2-oxoacetamide (MMA-203):

To the solution of ethyl(4-methoxyphenyl)(oxo)acetate(1.16 g, 5.58 mmol) in EtOH (10 mL) was added solution of aqueous ammonia (5 mL) at 0° C. and stirred for 2 h. MMA-203 was formed as white solid during reaction. The reaction mixture was poured on to ice for precipitate the product. The solid was filtered, washed one at a time with IPA, MTBE and hexane, dried on air to obtain pure target compound MMA-203 with 95% purity (0.715 g, 77% yield). Melting point 146° C.; ¹H NMR (400 MHz, DMSO-d₆) δ 8.24 (s, 1H), 7.97 (d, J=8.4 Hz, 2H), 7.90 (s, 1H), 7.10 (d, J=8.5 Hz, 2H), 3.86 (s, 3H); ¹³C NMR (126 MHz, DMSO-d₆) δ 189.74, 167.95, 164.61, 132.65, 126.07, 114.77, 56.18; HRMS (ESI), RT=1.061 min, m/z 180.0653[M+H]⁺, formula C₉H₉NO₃.

Preparation of 1-(4-methoxyphenyl)prop-2-yn-1-one (MMA-204):

4-methoxybenzoic acid (200 mg, 1,31 mmol) was dissolved in dry methelene chloride (5 ml). CDI was added portionally to the reaction mixture portionally. Reaction mixture was proceeded by US during 20 minutes. N,O-dimethylhydroxylamine hydrochloride (193 mg, 1.97 mmol) and TEA (199.5 mg, 1.97 mmol) were added. Reaction mixture was proceeded by US during 5 hours, washed by water, and purified by column chromatography (Eluent EtOAc¥flexane) to give N,4-dimethoxy-N-methylbenzamide (189 mg, 73,8% yield). Trimetilsilylacetylene (89 mg, 902 μmol) was dissolved in THF (5 mL) and cooled to 0° C. To this solution was added n-BuLi as a 2,5 solution in heexane (0.4 mL, 902 μmol), dropwise. After 20 min, Weinreb amide (160 mg, 820 μmol) was added dropwise via syringe, and the reaction was allowed to slowly warm to 25° C. over 2 h. The reaction was diluted with Et₂O, the mixture was poured into saturated aqueous citric acid solution, and the aqueous phase was extracted twice by EtOAc. Organic phases were dried with Na₂SO₄, decanted, and solvent was evaporated. The residue was purified by flash chromatography (Eluent EtOAc¥flexane) to give 1-(4-methoxyphenyl)-3-(trimethylsilyl)prop-2-yn-1-one (134 mg, 70,3% yield). 1-(4-methoxyphenyl)-3-(trimethylsilyl)prop-2-yn-1-one (250 mg, 1.08 mmol) was dissolved in THF (5 mL) and cooled to 0° C. To this solution was added potassium hydrofluoride (51 mg, 646 μmol) in 2 ml of water. Reaction mixture was stirred during 5 hours. via syringe, and the reaction was allowed to slowly warm to 25° C. over 2 h. The reaction was diluted with methelene chloride, the mixture was poured into saturated aqueous hydrochloric acid solution, and the aqueous phase was extracted twice by CH₂Cl₂. Organic phases were dried with Na2SO4, decanted, and solvent was evaporated. The residue was purified by flash chromatography (Eluent EtOAc¥flexane) to give MMA-204 (114 mg, 66% yield). Melting point 86° C.; ¹H NMR (400 MHz, Chloroform-d) δ 8.10 (d, J=8.8 Hz, 2H), 6.93 (d, J=8.8 Hz, 2H), 3.86 (s, 3H), 3.36 (s, 1H).¹³C NMR (126 MHz, Chloroform-d) δ 175.94, 164.79, 132.15, 131.16, 129.60, 113.96, 80.41, 80.04, 55.63; HRMS (ESI), RT=5.542 min, m/z 161.0597 [M+H]⁺, formula C₁₀H₈O₂.

Preparation of 1-(4-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)prop-2-en-1-one (MMA-205):

Phenol (3.65 g, 0.039 mol, 1 eq.) was dissolved in CH₂Cl₂ (20 mL) and cooled to 0° C. AlCl₃ (5.5 g, 0.0403 mol, 1.03 eq.) was added in few portions, keeping internal temperature below 5° C. and the reaction mixture was stirred for 10 minutes at the same temperature. The solution of 3-chloropropanoyl chloride (5 g, 0.0397 mol, 1.01 eq.) in CH₂Cl₂ (10 mL) was added dropwise, keeping internal temperature below 5° C., following by the additional stirring overnight. After the reaction was complete, the reaction mixture was quenched with H₂O (30 mL), the layers was separated and the water phase was extracted with CH₂Cl₂ (2×20 mL). Combined organic layers was washed with H₂O (2×10 mL) and brine (2×10 mL), dried over Na₂SO₄ and evaporated. Obtained crude product was purified by CC to give 3-chloro-1-(4-hydroxyphenyl)propan-1-one as orange oil (0.5 g, 7% yield).

To the precooled to 0° C. solution of 3-chloro-1-(4-hydroxyphenyl)propan-1-one (0.5 g, 0.0027 mol) in dihydropyran (5 mL) catalytical amount of TsOH*H₂O was added and the obtained mixture was stirred overnight. Evaporation of the solvent gives the crude product of 3-chloro-1-(4-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)propan-1-one (1 g, 0.0017 mol, about 45% yield), which was used in the next step without purification.

To the solution of 3-chloro-1-(4-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)propan-1-one (crude 1 g, ˜0.0017 mol) in CH₂Cl₂ (10 mL) at 0° C. the solution of TEA (1 g, 0.01 mol, 4-5eq.) in CH₂Cl₂ (10 mL) was added in a dropwise manner, following by additional stirring overnight. Evaporation of the solvent and purification of the obtained crude residue results in the target compound (MMA-205) (120 mg, 0.5 mmol, 25% yield); ¹H NMR (500 MHz, Chloroform-d) δ 7.95 (d, J=8.7 Hz, 2H), 7.17 (dd, J=17.1, 10.6 Hz, 1H), 7.12 (d, J=8.7 Hz, 1H), 6.43 (d, J=17.0 Hz, 1H), 5.88 (d, J=10.5 Hz, 1H), 5.53 (s, 1H), 3.91-3.80 (m, 1H), 3.66-3.59 (m, 1H), 2.07-1.95 (m, 1H), 1.90 (dd, J=7.1, 3.5 Hz, 2H), 1.80-1.47 (m, 3H); ¹³C NMR (126 MHz, Chloroform-d) δ 189.4 (s), 161.1 (s), 132.2 (s), 130.9 (s, J=7.1 Hz), 129.3 (s), 116.1 (s), 96.1 (s), 62.1 (s), 30.1 (s), 25.1 (s), 18.5 (s); LC-MS (ESI), RT=3.061 min, m/z 149.2 [M —C₅H₉O +H]⁺; HRMS (ESI), RT=1.085 min, m/z 149.06174 [M —C₅H₉O +H]⁺, formula C₉H₈O₂.

Results and Discussion: The syntheses of various novel vanillin derivatives with non-aldehyde reactive moieties that are metabolically stable and capable of forming stable covalent interactions with Hb are reported below and grouped into 2 classes of derivatives (Michael Acceptors, and oxoacetates).

-   -   Antisickling agent

Examples of Vanillin derivatives

Michael Acceptors

2-Oxoacetates

Example 2. Testing of the Compounds

In vitro Hemoglobin Modification, Oxygen Equilibrium and Antisickling Studies Using Human homozygous Sickle cell (SS) Blood

Materials and General Procedure: Leftover blood samples from patients with homozygous SS were obtained and utilized, based on an approved IRB protocol at the Children's Hospital of Philadelphia, with informed consent.

Experimental Procedure: The MMA series of compounds (MMA-202, MMA-204, and MMA-405) and the positive control vanillin were studied for their abilities to inhibit hypoxia-induced RBC sickling (RBC morphology study), increase Hb oxygen, and/or modify Hb (adduct formation) as previously published.^(31,33) Briefly, homozygous SS blood (hematocrit: 20%) suspensions were incubated under air in the absence or presence of 2 and/or 5 mM concentration of test compounds at 37° C. for 1 hr. Following, the suspensions were incubated under hypoxic condition (2.5% oxygen) at 37° C. for 2 hr. Aliquot samples were fixed with 2% glutaraldehyde solution without exposure to air, and then subjected to microscopic morphological analysis. The residual samples were washed in phosphate-buffered saline, and hemolyzed in hypotonic lysis buffer for the Hb oxygen equilibrium and Hb adduct experiments. For the Hb oxygen equilibrium study, approximately 100 μl aliquot samples from the lysate were added to 4 ml of 0.1M potassium phosphate buffer, pH 7.0, in a cuvette and subjected to hemoximetry analysis using Hemox™ Analyzer (TCS Scientific Corp.) to assess P₅₀ shifts. Another aliquot from the lysate was also subjected to Hb adduct formation study using cation-exchange HPLC (Hitachi D-7000 Series, Hitachi Instruments, Inc., San Jose, Calif.) with a weak cation-exchange column (Poly CAT A: 30 mm×4.6 mm, Poly LC, Inc., Columbia, Md.). To determine the binding of the MMA compounds to either α- or β-globin chains, the hemolysates were subjected to reversed-phase (RP) HPLC on a Hitachi D-7000 HSM Series, using a Jupiter 5 μm C-4 50×4.6 mm column, (Phenomenex®, Torrence, Calif.) and a gradient from 20% to 60% acetonitrile in 0.3% trifluoroacetic acid in 15 minutes, with UV detection at 215 nm.

Results and Discussion: The following MMA compounds, MMA-202, MMA-204, and MMA-205 were tested for their effect on Hb modification, Hb oxygen affinity and/or inhibition of RBC sickling at 1 mM and/or 2 mM and/or 5 mM as previously reported,^(31,33) and the results presented in FIGS. 2-9. The compounds MMA-202 and MMA-205 showed the most potent antisickling activities (FIG. 2). MMA-202 reduced RBC sickling in a dose-dependent manner to 48%, 28% and 15% at 1 mM, 2 mM and 5 mM, respectively (FIG. 2). MMA-205, the second most potent compound reduced sickling by 46% and 27% at 2 mM and 5 mM, respectively (FIG. 2). These values compare with 57% and 36% by vanillin, respectively. MMA-204 also showed moderate dose-dependent antisickling activities (57% and 44%, respectively; FIG. 2). FIG. 3 is a representative image of sickled cells under 2.5% O₂ gas in the presence of MMA-202 and MMA-205. It is apparent that the propenoyl and propynoyl reactive centers in these compounds are responsible for their antisickling activities.

We also tested the compounds for their effect on Hb modification and Hb oxygen affinity (at 2 mM and/or 5 mM) using aliquot samples from the same incubation sample used for the above antisickling study and the results shown in FIGS. 4-9. The high antisickling activity observed for MMA-202 and MMA-205 corresponded to proportion of increase in Hb oxygen affinity. At 2 mM and 5 mM, MMA-202 increased Hb oxygen affinity in dose-dependent manner by 13% and 51%, respectively, while MMA-205 also increased Hb affinity by 21% and 39%, respectively (FIGS. 4-7). These values compare with 12% and 27% by vanillin, respectively (FIG. 4). These two compounds also showed significant Hb modification (FIG. 8). Quite surprisingly, MMA-204, which showed relatively less potent antisickling activity than MMA-202 or MMA-205 increased Hb oxygen affinity the most by 29% and 62%, respectively (FIGS. 2 and 4).

A reverse-phase HPLC study conducted with MMA-202, MMA-204, and MMA-205 showed MMA-205 and MMA-204 to bind exclusively with the β-chain, while MMA-202 appears to bind to both the α-chain and β-chain (FIG. 9).

In Vitro Time-Dependent Hb Oxygen Equilibrium Studies Using Normal Whole Blood

Materials and General Procedure: Normal whole blood was collected from adult donors at the Virginia Commonwealth University after informed consent, in accordance with regulations of the IRB for Protection of Human.

Experimental procedure: MMA-202 and the control vanillin were used to conduct time-dependent studies on Hb oxygen equlibrium using normal whole blood. The study was performed in a 96-well deepwell (Thermo Scientific) plate, where each compound at 2 mM concentration was added to 600 μL of whole blood (30% hct) and incubated at 37° C. for 24 hr with shaking (at 140 rpm). Additionally, DMSO (1%) alone was also tested as a negative control. At 1, 4 and 24 hr time intervals, 75 μL aliquot of blood was removed from each well using a multichannel pipette and the reaction stopped immediately at −80° C. until ready for hemoximetry analysis using Hemox™ Analyzer (TCS Scientific Corp.) to assess P₅₀ shifts.³² The observed P₅₀ shifts values in % P₅₀ shifts were plotted as function of time [hrs].

Results and Discussion: The main purpose for developing these novel compounds was to improve on the pharmacokinetic properties of vanillin by replacing the aldehyde moiety with a more metabolically stable reactive center to reduce the apparent rapid oxidative metabolism. As noted above, vanillin and other aromatic aldehydes suffer from oxidative metabolism by aldehyde dehydrogenase, aldehyde oxidase in the liver, blood and other tissues that leads to short half-life and suboptimal bioavailability.^(31,33,42,43) The in vitro time-dependent Hb oxygen equilibrium studies with MMA-202 (2 mM) using freshly drawn normal whole blood showed that unlike the biological activity of vanillin, which declined rapidly to the baseline due to metabolism of the aldehyde, the activity of MMA-202 was sustained throughout the 24 hr experiment (FIG. 10). This is a significant improvement in the compound duration of action. Blood contains enzymes that are known to metabolize aromatic aldehydes and other compounds, and is a good predictor of the metabolic stability of compounds.⁴⁴⁻⁴⁶ Although, other metabolic routes, including the liver could reduce the pharmacologic activity of our novel compounds, we still expect significant improvement in the metabolic profile of these compounds in vivo.

CONCLUSION

Vanillin, and several of their aromatic aldehyde derivatives even though show promising as antisickling agents, their development into therapeutic agents have been hampered by poor PK properties due in most part by the metabolically unstable aldehyde moiety. We have developed novel compounds by derivatization the vanillin pharmacophore with a metabolically stable reactive centers that not only showed superior potency over vanillin, but most importantly, these compounds show improved in vitro metabolic profile. It is expected that the improved PK properties would translate into effective lower therapeutic dose.

Acknowledgment

This project was funded by the National Plan for Science, Technology, and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, the Kingdom of Saudi Arabia; Award number 14-BIO80-03. The authors also, acknowledge with thanks Science and Technology Unit, King Abdulaziz University, for technical support.

REFERENCES

-   1. Aliyu, Z. Y. et al. Prevalence and risk factors for pulmonary     artery systolic hypertension among sickle cell disease patients in     Nigeria. Am. J. Hematol. 83, 485-490 (2008). -   2. Piel, F. B., Steinberg, M. H. & Rees, D. C. Sickle Cell     Disease. N. Engl. J. Med. 377, 305 (2017). -   3. Poillon, W. N. & Kim, B. C. 2,3-Diphosphoglycerate and     intracellular pH as interdependent determinants of the physiologic     solubility of deoxyhemoglobin S. Blood 76, 1028-1036 (1990). -   4. Poillon, W. N., Kim, B. C., Labotka, R. J., Hicks, C. U. &     Kark, J. A. Antisickling effects of 2,3-diphosphoglycerate     depletion. Blood 85, 3289-3296 (1995). -   5. Poillon, W. N., Kim, B. C., Welty, E. V. & Walder, J. A. The     effect of 2,3-diphosphoglycerate on the solubility of     deoxyhemoglobin S. Arch. Biochem. Biophys. 249, 301-305 (1986). -   6. Sun, K. et al. Structural and Functional Insight of Sphingosine     1-Phosphate-Mediated Pathogenic Metabolic Reprogramming in Sickle     Cell Disease. Sci Rep 7, 15281 (2017). -   7. Sun, K. et al. Sphingosine-1-phosphate promotes erythrocyte     glycolysis and oxygen release for adaptation to high-altitude     hypoxia. Nat Commun 7, 12086 (2016). -   8. Zhang, Y. et al. Elevated sphingosine-1-phosphate promotes     sickling and sickle cell disease progression. J. Clin. Invest. 124,     2750-2761 (2014). -   9. Zhang, Y. et al. Detrimental effects of adenosine signaling in     sickle cell disease. Nat. Med. 17, 79-86 (2011). -   10. Ghatge, M. S. et al. Crystal structure of carbonmonoxy sickle     hemoglobin in R-state conformation. J. Struct. Biol. 194, 446-450     (2016). -   11. Ferrone, F. A. & Rotter, M. A. Crowding and the polymerization     of sickle hemoglobin. J. Mol. Recognit. 17, 497-504 (2004). -   12. Cretegny, I. & Edelstein, S. J. Double strand packing in     hemoglobin S fibers. J. Mol. Biol. 230, 733-738 (1993). -   13. Eaton, W. A. & Hofrichter, J. Sickle cell hemoglobin     polymerization. Adv. Protein Chem. 40, 63-279 (1990). -   14. Harrington, D. J., Adachi, K. & Royer, W. E. The high resolution     crystal structure of deoxyhemoglobin S. J. Mol. Biol. 272, 398-407     (1997). -   15. Bunn, F. Molecular, Genetic and Clinical Aspects. in In     Hemoglobin: 502-564 (W. B. Saunders company, 1986). -   16. Akinsheye, I. & Klings, E. S. Sickle cell anemia and vascular     dysfunction: the nitric oxide connection. J. Cell. Physiol. 224,     620-625 (2010). -   17. De Franceschi, L. Pathophisiology of sickle cell disease and new     drugs for the treatment. Mediterr J Hematol Infect Dis 1, e2009024     (2009). -   18. Belcher, J. D. et al. Transgenic sickle mice have vascular     inflammation. Blood 101, 3953-3959 (2003). -   19. Mvalo, T. et al. Increasing hydroxyurea use in children with     sickle cell disease at Kamuzu Central Hospital, Malawi. Blood Adv 2,     30-32 (2018). -   20. Brandow, A. M. & Panepinto, J. A. Hydroxyurea use in sickle cell     disease: the battle with low prescription rates, poor patient     compliance and fears of toxicities. Expert Rev Hematol 3, 255-260     (2010). -   21. Sinha, C. B., Bakshi, N., Ross, D. & Krishnamurti, L. From trust     to skepticism: An in-depth analysis across age groups of adults with     sickle cell disease on their perspectives regarding hydroxyurea.     PloS one 13, e0199375 (2018). -   22. L-glutamine (Endari) for sickle cell disease. Med Lett Drugs     Ther 60, 21-22 (2018). -   23. Kaufman, M. Pharmaceutical approval update: L-glutamine oral     powder (Endari). Pharmacy and Therapeutics 42, 620-21 (2017). -   24. Cieri-Hutcherson, N. E., Hutcherson, T. C., Conway-Habes, E. E.,     Burns, B. N. & White, N. A. Systematic Review of 1-glutamine for     Prevention of Vaso-occlusive Pain Crisis in Patients with Sickle     Cell Disease. Pharmacotherapy (2019) doi:10.1002/phar.2329. -   25. Ataga, K. I. et al. Crizanlizumab for the prevention of pain     crises in sickle cell disease. New England Journal of Medicine 376,     (2017). -   26. Vichinsky, E. et al. A Phase 3 randomized trial of voxelotor in     sickle cell disease. New England Journal of Medicine (2019)     doi:10.1056/NEJMoa1903212. -   27. Oder, E., Safo, M. K., Abdulmalik, 0. & Kato, G. J. New     developments in anti-sickling agents: can drugs directly prevent the     polymerization of sickle haemoglobin in vivo? British Journal of     Haematology vol. 175 24-30 (2016). -   28. Safo, M. K. & Kato, G. J. Therapeutic strategies to alter the     oxygen affinity of sickle hemoglobin. Hematology/Oncology Clinics of     North America (2014) doi:10.1016/j.hoc.2013.11.001. -   29. Safo, M. K. & Bruno, S. Allosteric Effectors of Hemoglobin:     Past, Present and Future. in Chemistry and Biochemistry of Oxygen     Therapeutics: From Transfusion to Artificial Blood (eds.     Mozzarelli, A. & and Bettati, S.) 285-300 (John Wiley & Sons, Ltd,     2011). -   30. Safo, M. K., Ahmed, M. H., Ghatge, M. S. & Boyiri, T.     Hemoglobin-ligand binding: understanding Hb function and allostery     on atomic level. Biochim. Biophys. Acta 1814, 797-809 (2011). -   31. Abdulmalik, O. et al. 5-Hydroxymethyl-2-furfural modifies     intracellular sickle haemoglobin and inhibits sickling of red blood     cells. British Journal of Haematology 128, 552-561 (2005). -   32. Xu, G. G. et al. Design, Synthesis, and Biological Evaluation of     Ester and Ether Derivatives of Antisickling Agent 5-HMF for the     Treatment of Sickle Cell Disease. Molecular Pharmaceutics (2017)     doi:10.1021/acs.molpharmaceut.7b00553. -   33. Safo, M. K. et al. Structural Basis for the Potent Antisickling     Effect of a Novel Class of Five-Membered Heterocyclic Aldehydic     Compounds. J. Med. Chem. 47, 4665-4676 (2004). -   34. Abdulmalik, O. et al. Crystallographic analysis of human     hemoglobin elucidates the structural basis of the potent and dual     antisickling activity of pyridyl derivatives of vanillin Acta     Crystallographica Section D: Biological Crystallography vol. 67     920-928 (2011). -   35. Deshpande, T. M. et al. Rational modification of vanillin     derivatives to stereospecifically destabilize sickle hemoglobin     polymer formation. Acta Crystallographica Section D: Structural     Biology 74, 956-964 (2018). -   36. Pagare, P. P. et al. Rational design of pyridyl derivatives of     vanillin for the treatment of sickle cell disease. Bioorg. Med.     Chem. 26, 2530-2538 (2018). -   37. Nnamani, I. N. et al. Pyridyl derivatives of benzaldehyde as     potential antisickling agents. Chem. Biodivers. 5, 1762-1769 (2008). -   38. Zhang, C. et al. Anti-sickling effect of MX-1520, a prodrug of     vanillin: an in vivo study using rodents. Br.J.Haematol. 125,     788-795 (2004). -   39. Omar, A. M. et al. Identification of a novel class of covalent     modifiers of hemoglobin as potential antisickling agents. Org.     Biomol. Chem. 13, 6353-6370 (2015). -   40. Nakagawa, A. et al. A Triazole Disulfide Compound Increases the     Affinity of Hemoglobin for Oxygen and Reduces the Sickling of Human     Sickle Cells. Mol. Pharm. 15, 1954-1963 (2018). -   41. Nakagawa, A. et al. Identification of a small molecule that     increases hemoglobin oxygen affinity and reduces SS erythrocyte     sickling. ACS Chem. Biol. 9, 2318-2325 (2014). -   42. Obied &, T., Venitz, J. 5-hydroxy methyl furfural (5-HMF)     metabolism in hepatic cytosol from mice, rats, dogs, and humans. in     23 rd Annual Meeting (The AAPS Journal, 2009). -   43. Abraham, D. J. et al. Vanillin, a potential agent for the     treatment of sickle cell anemia. Blood 77, 1334-1341 (1991). -   44. Godfrey, V. B., Chen, L. J., Griffin, R. J., Lebetkin, E. H. &     Burka, L. T. Distribution and metabolism of     (5-hydroxymethyl)furfural in male F344 rats and B6C3F1 mice after     oral administration. J. Toxicol. Environ. Health Part A 57, 199-210     (1999). -   45. Yoshida, A., Rzhetsky, A., Hsu, L. C. & Chang, C. Human aldehyde     dehydrogenase gene family Eur. J. Biochem. 251, 549-557 (1998). -   46. Vasiliou, V., Pappa, A. & Petersen, D. R. Role of aldehyde     dehydrogenases in endogenous and xenobiotic metabolism. Chem. Biol.     Interact. 129, 1-19 (2000).

While the invention has been described in terms of its preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. Accordingly, the present invention should not be limited to the embodiments as described above, but should further include all modifications and equivalents thereof within the spirit and scope of the description provided herein. 

We claim:
 1. A method of enhancing oxygen delivery from hemoglobin to hypoxic tissue by administering to a subject a therapeutically effective amount of a compound, or pharmaceutically acceptable salt or solvate thereof, selected from the group consisting of


2. The method of claim 1 wherein said therapeutically effective amount of said compound is sufficient to inhibit red blood cell (RBC) sickling.
 3. The method of claim 1 wherein the compound, or pharmaceutically acceptable salt or solvate thereof is one of


4. The method of claim 1 wherein the compound, or pharmaceutically acceptable salt or solvate thereof is one of 